[libcxx] r192038 - Implement LWG issue 2275 'forward_as_tuple should be constexpr'

[Richard Smith]

On Sat, Oct 5, 2013 at 11:46 AM, Marshall Clow <mclow.lists at gmail.com>wrote:

> Author: marshall
> Date: Sat Oct  5 13:46:37 2013
> New Revision: 192038
>
> URL: http://llvm.org/viewvc/llvm-project?rev=192038&view=rev
> Log:
> Implement LWG issue 2275 'forward_as_tuple should be constexpr'
>

Does LWG have a distinction between a DR (applies to previous standards)
and an extension (only applies to new standard), like CWG does? Or do I
have to #define something extra to get C++11 plus LWG-approved bug fixes?


> Modified:
>     libcxx/trunk/include/tuple
>
> libcxx/trunk/test/utilities/tuple/tuple.tuple/tuple.creation/forward_as_tuple.pass.cpp
>
> Modified: libcxx/trunk/include/tuple
> URL:
> http://llvm.org/viewvc/llvm-project/libcxx/trunk/include/tuple?rev=192038&r1=192037&r2=192038&view=diff
>
> ==============================================================================
> --- libcxx/trunk/include/tuple (original)
> +++ libcxx/trunk/include/tuple Sat Oct  5 13:46:37 2013
> @@ -73,7 +73,7 @@ public:
>  const unspecified ignore;
>
>  template <class... T> tuple<V...>  make_tuple(T&&...); // constexpr in
> C++14
> -template <class... T> tuple<ATypes...> forward_as_tuple(T&&...) noexcept;
> +template <class... T> tuple<ATypes...> forward_as_tuple(T&&...) noexcept;
> // constexpr in C++14
>  template <class... T> tuple<T&...> tie(T&...) noexcept;
>  template <class... Tuples> tuple<CTypes...> tuple_cat(Tuples&&... tpls);
> // constexpr in C++14
>
> @@ -833,14 +833,6 @@ make_tuple(_Tp&&... __t)
>  template <class... _Tp>
>  inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
>  tuple<_Tp&&...>
> -__forward_as_tuple(_Tp&&... __t) _NOEXCEPT
> -{
> -    return tuple<_Tp&&...>(_VSTD::forward<_Tp>(__t)...);
> -}
> -
> -template <class... _Tp>
> -inline _LIBCPP_INLINE_VISIBILITY
> -tuple<_Tp&&...>
>  forward_as_tuple(_Tp&&... __t) _NOEXCEPT
>  {
>      return tuple<_Tp&&...>(_VSTD::forward<_Tp>(__t)...);
> @@ -1041,7 +1033,7 @@ struct __tuple_cat<tuple<_Types...>, __t
>      typename __tuple_cat_return_ref<tuple<_Types...>&&, _Tuple0&&>::type
>      operator()(tuple<_Types...> __t, _Tuple0&& __t0)
>      {
> -        return
> __forward_as_tuple(_VSTD::forward<_Types>(get<_I0>(__t))...,
> +        return forward_as_tuple(_VSTD::forward<_Types>(get<_I0>(__t))...,
>
>  get<_J0>(_VSTD::forward<_Tuple0>(__t0))...);
>      }
>
> @@ -1056,7 +1048,7 @@ struct __tuple_cat<tuple<_Types...>, __t
>             tuple<_Types..., typename __apply_cv<_Tuple0, typename
> tuple_element<_J0, _T0>::type>::type&&...>,
>             typename __make_tuple_indices<sizeof ...(_Types) +
> tuple_size<_T0>::value>::type,
>             typename __make_tuple_indices<tuple_size<_T1>::value>::type>()
> -                           (__forward_as_tuple(
> +                           (forward_as_tuple(
>                                _VSTD::forward<_Types>(get<_I0>(__t))...,
>                                get<_J0>(_VSTD::forward<_Tuple0>(__t0))...
>                              ),
>
> Modified:
> libcxx/trunk/test/utilities/tuple/tuple.tuple/tuple.creation/forward_as_tuple.pass.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/libcxx/trunk/test/utilities/tuple/tuple.tuple/tuple.creation/forward_as_tuple.pass.cpp?rev=192038&r1=192037&r2=192038&view=diff
>
> ==============================================================================
> ---
> libcxx/trunk/test/utilities/tuple/tuple.tuple/tuple.creation/forward_as_tuple.pass.cpp
> (original)
> +++
> libcxx/trunk/test/utilities/tuple/tuple.tuple/tuple.creation/forward_as_tuple.pass.cpp
> Sat Oct  5 13:46:37 2013
> @@ -51,6 +51,15 @@ test2a(const Tuple& t)
>      assert(std::get<1>(t) == 'a');
>  }
>
> +#if _LIBCPP_STD_VER > 11
> +template <class Tuple>
> +constexpr int
> +test3(const Tuple& t)
> +{
> +    return std::tuple_size<Tuple>::value;
> +}
> +#endif
> +
>  int main()
>  {
>      {
> @@ -67,5 +76,8 @@ int main()
>          double i = 2.5;
>          char c = 'a';
>          test2a(std::forward_as_tuple(i, c));
> +#if _LIBCPP_STD_VER > 11
> +        static_assert ( test3 (std::forward_as_tuple(i, c)) == 2, "" );
> +#endif
>      }
>  }
>
>
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